Field of the Invention
The present invention relates to a wireless communication system, and more particularly, to various methods of reporting channel status information to a base station and apparatus for supporting the same.
Discussion of the Related Art
Generally, a wireless communication system is developing to diversely cover a wide range to provide such a communication service as an audio communication service, a data communication service and the like. The wireless communication is a sort of a multiple access system capable of supporting communications with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). For example, the multiple access system may include one of CDMA (code division multiple access) system, FDMA (frequency division multiple access) system, TDMA (time division multiple access) system, OFDMA (orthogonal frequency division multiple access) system, SC-FDMA (single carrier frequency division multiple access) system and the like.
A user equipment periodically can transmit channel status information (CSI) to a base station. Alternatively, if a base station makes a request, the user equipment can aperiodically report CSI to the base station.
In LTE-A system, in case that a CSI reference resource belongs to a CSI measurement set, a user equipment just reports a CSI corresponding to the CSI reference resource to a base station. However, if a CSI reference resource does not belong to any CSI measurement set, it may cause a problem that a CSI to be reported does not exist.